The present invention is generally related to scanning beam devices, systems, and methods. More specifically, the present invention can provide distance measurements, angle measurements, and/or other geometrical relationships between a scanned beam device and a surface, such as between a scanning fiber endoscope and an internal tissue, typically by identifying specular reflection signals from the surface.
There is a growing market for micro-optical devices, and particularly for small image acquisition systems (e.g., cameras). Micro-optical systems having appropriate optical characteristics and size may find use in a variety of applications including minimally invasive medical imaging (and particularly in flexible endoscopes), in surveillance, in industrial inspection and repair, in machine and robotic vision systems, in micro-barcode scanners, and the like. Scanning beam systems may fill the needs in some or all of these applications, although challenges remain in providing the desired optical characteristics at a reasonable cost.
An improved scanning beam system has been under development at the University of Washington to more fully meet the needs for micro-optical image acquisition systems. This improved scanning beam system makes use of a cantilevered optical fiber that can be scanned in one or two dimensions. Light is projected out of the end of the optical fiber, through a lens system, and onto a target area of a surface. To acquire an image, a time series of backscattered reflected light is captured with one or more light detector(s) of the system. More specifically, signals from one or more photodetector(s) correspond to the brightness of the small portion of the image illuminated by the fiber at that point in time. As the motion of the optical fiber is predictable and repeatable, the reflected backscattered light intensity measured at the detector(s) can be sequentially correlated with known positions of the optical fiber. This allows a two-dimensional image to be generated one pixel at a time. Some exemplary scanning fiber devices are described in U.S. Pat. No. 6,294,775B1 (Seibel) and U.S. Pat. No. 6,563,105B2 (Seibel), and in U.S. Patent Application Publication Nos. 2001/0055462A1 (Seibel) and 2002/0064341A1 (Seibel), the complete disclosures of which are incorporated herein by reference.
The images obtained by a scanning fiber endoscope or other scanning fiber device are two-dimensional. In other words, these images appear similar to an image taken with a traditional camera. Hence, these images may contain somewhat limited depth information. Nonetheless, in comparison to traditional image capture devices, the new scanning fiber technology offers many advantages. The small mass of the optical fiber allows high scan angles at video rates. Optical fiber scanners also have a small volume, optionally being packaged into a cylinder having a diameter of less than 1 mm. The optical capabilities and small package size make these new scanning beam devices particularly beneficial for use in endoscopes.
While scanning fiber systems appear to be very promising for use in a number of different applications, additional improvements would still be desirable. For example, distance and other geometrical information can be very useful when working with an endoscope. It would be particularly valuable for an operator to know a distance between, for example, the tip of an endoscope and a tissue surface or tissue structure being viewed. Additional geometrical information regarding the tissue surface or structure may also be of use.
In light of the above, it would generally be desirable to provide improved scanned beam devices, systems, and methods. It would be particularly desirable if these improved devices could provide distance measurement and/or other geometric information, preferably in combination with the imaging capabilities of the recently developed scanning fiber devices. Ideally, this additional geometrical information might be provided without significantly increasing the size, complexity, or cost of these advantageous new image capturing devices.